1. Field of the Invention
This invention relates to a subscriber line control device for accommodating either only analog circuits or both analog and digital subscriber circuits and for controlling subscriber lines.
2. Description of the Related Art
Although a digital subscriber line control device accommodating digital subscriber circuits conventionally has performed a digital subscriber line control, a line processor (LPR) has performed an analog subscriber line control, such as a supervision of a call origination and that of a dial pulse.
Generally, because a digital subscriber line control has a predetermined protocol between a subscriber terminal and a network, even if the digital subscriber line control device cannot perform its process in time, the terminal cannot perform the next procedure without a response from the network side.
Since an analog subscriber line control, on the other hand, performs its processes such as an emission of a dial pulse from an analog subscriber terminal device independently of a response from the network side, dial pulses need to be supervised every certain number of cycles, the faster the processing speed is, the more subscribers are accommodated.